Al-Si-Mg ALLOY AND METHOD OF PRODUCING THE SAME

ABSTRACT

An Al—Si—Mg-based aluminum alloy includes about 1.2 to about 1.4 wt % of Si, about 0.6 to about 0.75 wt % of Mg, about 0.8 to about 1.0 wt % of Sn, and Al and impurities as the balance on the basis of the total weight of the aluminum alloy.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on, and claims priority from, Korean Application Serial Number 10-2009-0018109, filed on Mar. 3, 2009, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Field

The present disclosure relates to an Al—Si—Mg-based aluminum alloy that has excellent machinability and a method for producing the same.

2. Discussion of the Related Technology

A general 6000 series (Al—Mg—Si-based) wrought aluminum alloy is commercially used as part materials such as ABS (Anti-lock Breaking system) pump housings for vehicles, ESC (Electronic Stability Control) pump housings and the like.

However, in the case of the general 6000 series (Al—Mg—Si-based) wrought aluminum alloy, since the machinability is not good, length of processed chips become long. The long chips curl processing tools and increase a load applied to the tools while processing is carried out. Accordingly, there are disadvantages in that poor processing and damage to processing tools are caused, a processing speed is lowered, and the quality of processed products is lowered.

Therefore, in the case of when a general 6000 series wrought aluminum alloy are used as part materials such as ABS (Anti-lock Breaking system) pump housings or ESC (Electronic Stability Control) pump housings, there are problems in that a production cost is increased and the quality of parts is lowered.

SUMMARY

Embodiments of the present invention help overcome the drawbacks in the related art and it is an aspect of the invention to provide wrought aluminum alloy, which has high machinability and does not cause problems such as chip curling while processing is carried out or a damage to processing tools by changing the composition of the 6000 series wrought aluminum alloy that is generally used in the related art to improve the machinability, and a method for producing the same.

One aspect of the present invention provides an Al—Si—Mg-based aluminum alloy which comprises about 1.2 to about 1.4 wt % of Si, about 0.6 to about 0.75 wt % of Mg, about 0.8 to about 1.0 wt % of Sn, and Al and impurities as the balance on the basis of the total weight of the aluminum alloy.

Further, a method for producing an Al—Si—Mg-based aluminum alloy according to one embodiment of the present invention comprises the steps of preparing a composition for an Al—Si—Mg-based aluminum alloy that includes about 1.2 to about 1.4 wt % of Si, about 0.6 to about 0.75 wt % of Mg, about 0.8 to about 1.0 wt % of Sn, and Al and impurities as the balance on the basis of the total weight of the aluminum alloy; producing the composition for an aluminum alloy into billets through a continuous casting process; and performing uniform heat treatment, extrusion, stretching, and aging heat treatment in respects to the produced billets in the above step, wherein the aging heat treatment is carried out at about 130 to about 150° C.

Since the wrought aluminum alloy according to one embodiment of the present invention has very excellent machinability and does not cause problems such as chip curling while processing is carried out or a damage to processing tools, a processing cycle time is shortened. In addition, the defect ratio of processed products is largely lowered, the quality of processed products is improved, and the residual amount of burr is lowered, such that it is easy to remove and wash burrs. Therefore, the wrought aluminum alloy according to one embodiment of the present invention largely contributes to an improvement of productivity while processing is carried out and provides a large cost reduction effect.

BRIEF DESCRIPTION OF THE DRAWINGS

For better understanding of the nature and features of the present invention, reference should be made to the following detailed description with the accompanying drawings, in which:

FIG. 1 illustrates pictures of shapes of chips that are generated while specimens of the aluminum alloys that are produced in Example 1 and Comparative Examples 1 to 3 are processed [(a) Comparative Example 1, (b) Comparative Example 2, (c) Comparative Example 3, and (d) Example 1].

DETAILED DESCRIPTION OF EMBODIMENTS

The present disclosure relates to an Al—Si—Mg-based aluminum alloy that comprises 1.2 to 1.4 wt % of Si, 0.6 to 0.75 wt % of Mg, 0.8 to 1.0 wt % of Sn, and Al and impurities as the balance on the basis of the total weight of the aluminum alloy.

The aluminum alloy according to one embodiment of the present invention is characterized in that Sn that is a low melting point metal is added in order to improve processing characteristics of the 6000 series wrought aluminum alloy material and the contents of Si and Mg are optimized in order to prevent reduction of physical properties of the material according to the addition of Sn and to improve the physical properties thereof.

In the present disclosure, “impurities” means undesired components that are included in the course of producing the alloy.

Among the components that are included in the aluminum alloy according to one embodiment of the present invention, it is preferable that Si is included in a content in the range of 1.2 to 1.4 wt %. If it is included in a content of less than 1.2 wt %, there is a problem in that hardness of the alloy is lowered. If it is included in a content of more than 1.4 wt %, since a reduction in casting speed occurs according to the high alloy content while wrought billet is produced, the productivity is reduced, an extrusion speed is lowered according to an increase in fluidity stress of a material in extrusion, and the quality of the surface thereof is lowered. In addition, because of an increase in hardness value according to the effect of excessive Excess-Si, there is a problem in that an amount of tool abrasion is increased.

Among the components that are included in the aluminum alloy according to one embodiment of the present invention, it is preferable that Mg is included in a content in the range of 0.6 to 0.75 wt %. If it is included in a content of less than 0.6 wt %, a possibility of burning while processed chips are generated is increased, the content of the Mg₂Si precipitate phase that functions to reinforce physical properties is relatively lowered because of the generation of Mg—Sn-based precipitate phases, such that physical properties of the material are lowered. If it is included in a content of more than 0.75 wt %, since a fibrous structure in a base is reinforced, the length of the processed chip becomes long, and thus the machinability is lowered.

Among the components that are included in the aluminum alloy according to one embodiment of the present invention, Sn generates Mg—Sn-based precipitate phases with the Mg, and the precipitate phases function to break chips while processing is carried out, thus improving the machinability. Therefore, in accordance with the content of Sn, these characteristics are excessive or poor. If Sn is included in a content of less than 0.8 wt %, the improvement effect of the machinability is insignificant. If Sn is included in a content of more than 1.0 wt %, the size of processed chip is small, but a possibility of generation of damage to tools is increased while processing is carried out because of burning between the processed chips.

It is preferable that the aluminum alloy according to one embodiment of the present invention further includes 0.50 to 0.70 wt % of Mn on the basis of the total weight of the aluminum alloy. Mn is an element that suppresses the generation of the precipitate shape of the compound such as AlFeSi and is effective to make crystal grains fine in order to improve strength. If Mn is included in a content of less than 0.50 wt %, there is a high possibility of generation of the precipitate shape of the compound such as AlFeSi and the fine crystal grain effect is insignificant. If Mn is included in a content of more than 0.70 wt %, there is a problem in that strength is lowered.

In addition, the aluminum alloy of one embodiment of the present invention may further include one or more that are selected from the group consisting of 0.001 to 0.50 wt % of Fe, 0.01 to 0.10 wt % of Cu, 0.01 to 0.25 wt % of Cr, and 0.01 to 0.20 wt % of Zn on the basis of the total weight of the aluminum alloy. If the content of the component exceeds the above range, a reduction in physical properties may occur in accordance with the generation of the compound between metals, and the extrudability is lowered, such that the productivity is lowered.

In addition, other components other than the above-mentioned components can be included in a content of 0.15 wt % or less. It is preferable that the aluminum alloy of one embodiment of the present invention have the content of fine elements controlled as described above in order to suppress the generation of the compound between different metals.

In addition, the present disclosure relates to a method for producing an Al—Si—Mg-based aluminum alloy, which comprises the steps of preparing a composition for an Al—Si—Mg-based aluminum alloy that includes 1.2 to 1.4 wt % of Si, 0.6 to 0.75 wt % of Mg, 0.8 to 1.0 wt % of Sn, and Al and impurities as the balance on the basis of the total weight of the aluminum alloy; producing the composition for an aluminum alloy into billets through a continuous casting process; and performing uniform heat treatment, extrusion, stretching, and aging heat treatment in respects to the produced billets in the above step, wherein the aging heat treatment is carried out at 130 to 180° C.

Among the above production methods, the remaining process except for the composition for the Al—Si—Mg-based aluminum alloy and the temperature of the aging heat treatment may be carried out by using the method that is known in the art. The aging heat treatment may change the temperature of the heat treatment in accordance with the required physical properties. Because of the characteristics of the above composition, for example, a change in precipitation dynamics of the compound by the addition of Sn, unlike a known method, it is preferable that the temperature of the aging heat treatment is in the range of 130 to 150° C. More preferably, the heat treatment process is carried out at 140° C. in order to form the uniform precipitate phase distribution and to prevent the coarse precipitation.

In the production method, it is more preferable that the composition for the aluminum alloy further include 0.50 to 0.70 wt % of Mn on the basis of the total weight of the aluminum alloy. In addition, the aluminum alloy according to one embodiment of the present invention may further include one or more that are selected from the group consisting of 0.001 to 0.50 wt % of Fe, 0.01 to 0.10 wt % of Cu, 0.01 to 0.25 wt % of Cr, and 0.01 to 0.20 wt % of Zn on the basis of the total weight of the aluminum alloy.

Hereinbelow, embodiments of the present invention will be described in detail with reference to Examples. However, the present invention should not be construed as being limited to the Examples set forth herein. Rather, the following Examples may be changed appropriately by those skilled in the art within the concept of the invention.

Example 1 to Comparatives 1 to 3 Production of the Aluminum Alloy

In order to confirm the characteristics (tensile strength, yield strength, and elongation ratio) of the aluminum alloy according to one embodiment of the present invention, the aluminum alloy samples of Example 1 and Comparative Examples 1 to 3 were produced by using the component compositions of the following Table 1.

TABLE 1 Si Mg Sn Mn Fe Cu Cr Zn Al and impurities Example 1 1.25 0.68 0.85 0.55 0.20 0.03 0.15 0.02 residual amount Comparative 1.0 0.55 1.0 0.55 0.20 0.03 0.15 0.02 residual Example 1 amount Comparative 1.2 0.95 1.0 0.55 0.20 0.03 0.15 0.02 residual Example 2 amount Comparative 1.2 0.55 1.0 0.55 0.20 0.03 0.10 0.02 residual Example 3 amount (unit: wt %)

Experimental Example 1 Evaluation of the Machinability and the Hardness of the Aluminum Alloy

The machinability and the hardness of the aluminum alloy samples that were produced in Example 1 and Comparative Examples 1 to 3 were evaluated, and the results were described in the following Table 2.

TABLE 2 Si Mg Sn machinability hardness Example 1 1.25 0.65 0.85 excellent excellent (no chip curling, (HB 104 to 110) no damage to tools, and small residual amount of burr Comparative 1.0 0.55 1.0 Normal poor Example 1 (HB 88 to 90) Comparative 1.2 0.95 1.0 poor normal Example 2 (chip curling (HB 102 to 105) occurs) Comparative 1.2 0.55 1.0 Poor normal Example 3 (a damage to (HB 98 to 100) drill having a small diameter)

Experimental Example 2 Evaluation of the Tensile Strength, Yield Strength and Elongation of the Aluminum Alloy

The tensile strength, yield strength and elongation ratio of the samples of Example 1 and the commercial aluminum alloy were evaluated, and the results were described in the following Table 3.

TABLE 3 Tensile Yield elongation Notice (MPa) (MPa) ratio (%) Example 1 371 337 14.7 6082 357 336 13.6 commercial alloy

From data described in Table 3, it can be seen that the aluminum alloy according to one embodiment of the present invention is more excellent than the 6082 commercial alloy in views of the tensile strength, yield strength and elongation ratio.

Experimental Example 3 Evaluation of the Processing Speed of the Aluminum Alloy

The machinability of the samples of Example 1 and the 6082 commercial alloy were evaluated by using four kinds of drills having the small diameter, and the results were described in the following Table 4.

TABLE 4 Commercial notice products Example 1 remark Φ 3.275 spindle speed (rpm) 15,000 15,000 100% Feeding speed 2,000 4,000 improvement Φ 3.63 spindle speed (rpm) 15,000 15,000  10% Feeding speed 3,000 3,500 improvement Φ 4.64 spindle speed (rpm) 12,000 13,500 Feeding speed 1,500 1,800 Φ 5.25 spindle speed (rpm) 10,000 11,000 Feeding speed 1,300 1,500 

1. An Al—Si—Mg-based alloy comprising: Si in an amount of about 1.2 to about 1.4 wt %; Mg in an amount of about 0.6 to about 0.75 wt %; Sn in an amount of about 0.8 to about 1.0 wt %; and Al, wherein each amount is with reference to the total weight of the alloy.
 2. The alloy as defined in claim 1, further comprising Mn in an amount of about 0.50 to about 0.70 wt % with reference to the total weight of the alloy.
 3. The alloy as defined in claim 1, further comprising one or more selected from the group consisting of: Fe in an amount of about 0.001 to about 0.50 wt %; Cu in an amount of about 0.01 to about 0.10 wt %; Cr in an amount of about 0.01 to about 0.25 wt %; and Zn in an amount of about 0.01 to about 0.20 wt %, wherein each amount is with reference to the total weight of the alloy.
 4. A method for producing an Al—Si—Mg-based alloy, the method comprising: providing a composition for an Al—Si—Mg-based alloy, the composition comprising: Si in an amount of about 1.2 to about 1.4 wt %; Mg in an amount of about 0.6 to about 0.75 wt %; Sn in an amount of about 0.8 to about 1.0 wt %; and Al, wherein each amount is with reference to the total weight of the composition; forming the composition into one or more billets through a continuous casting process; and subjecting the one or more billets to stretching, and aging heat treatment, wherein the aging heat treatment is carried out at a temperature between about 130 and 150° C.
 5. The method as defined in claim 4, wherein the composition further comprising Mn in an amount of about 0.50 to about 0.70 wt % with reference to the total weight of the composition.
 6. The method as defined in claim 5, wherein the composition further includes one or more selected from the group consisting of: Fe in an amount of about 0.001 to about 0.50 wt %; Cu in an amount of about 0.01 to about 0.10 wt %; Cr in an amount of about 0.01 to about 0.25 wt %; and Zn in an amount of about 0.01 to about 0.20 wt %, wherein each amount is with reference to the total weight of the composition. 